Method for asphalt saturation



Patented June 6,

UNITED V STATES PATENT} I 2 ,350,649 OFFICE METHOD FOR ASPHALTSATURATION New York No Drawing. Application July 2, 1941,

Serial No. 400,814

7 Claims. (01. 117.-168) This invention relatesto a non-foaming asphaltsaturant and to the manufacture of that product.

In the manufacture of linoleum, waterproofing materials for the buildingtrade, waterproofing packing materials, and similar fibrous materials,it has been customary to saturate burlap, and other fabrics, as well aspaper, felt, and other fibrous materials, with melted bituminoussat--urants. In modern plants this process is accomplished by pulling acontinuous sheet of fabric or paper through a vat containing the hotasphalt. vThere is always some moisture present in the fabric and sheetpaper which suddenly evaporates when the fabric or sheet paper isimmersed in the asphalt bath which is at temperatures above the boilingpoint of water. Usually the temperatures of such asphalt baths arebetween 250 and 450 F.

The foaming of the asphalt associated with .the evaporation of waterfrom the sheet is a highly undesirable feature both from the standpointof efficiency of the plant and quality of the product.

It has been observed that asphalts derived from certain crudes produce amore tenacious foam while asphalts from selected crudes such as Mexican,produce a foam which subsides very quickly and does not causevdifllculties in the process of saturation.

The methodof control of foaming characteristics of saturant asphaltspresently used in the art is wholly one of control by selecting thesource of crude from which the asphalt is produced, no method as yethavingbeen developed for producing non-foaming saturants from sourcesother than those wherein material of the grade desired is fortuitouslyendowed with the property.

This invention has for its object the provision of a non-foaming asphaltsaturant and a method of producing that saturant, which is notrestricted to the source materials formerly used. A

principal object of this invention is the production of high qualitynon-foaming asphalt saturants from materials not heretofore believed tobe capable of producing such saturants.

Conventional methods of preparing satisfactory asphalt'saturantscomprise'first selecting a suitable crude oil, say Mexican asphalticcrude,

and reducing it to the desired consistency by mm, and then cutting thatbase back to specification with a liquid or semi-liquid petroleum oil,which may be either a residual product or a distillate, it is possibleto control the foaming characteristics of the asphalt saturant.

We can use as a raw material for the preparation of such a hard base anyhydrocarbon residual product with a viscosity-gravity constant of .890minimium. The conception of, V. G. C. for

expressing the naphthenicity, aromaticity or paraifinicity of thehydrocarbon fractions has been introduced by Hill & Coates in 1928 (seeIndustrial 8: Engineering Chemistry 1928, page 641) Solvent tars such asobtained from single and double solvent refining operations; pressureback to the form the finished saturant may be;

any oil of the following characteristics: Viscosity index, 50 minimumViscosity from 40" Saybolt Universal 100 F.

to 4000" Saybolt Furol 210 F.-

In making the asphaltic base for the saturant, the base should bereduced to a softening point at least five degrees Fahrenheit, asexpressed by the Ring and Ball A. s. T. M. method D36-26 above thespecification desired for the final saturant.

The amount of cutback oil to be used may, of

course, vary, not-only with the physical characteristics of the cut-backoil itself, but also with the excess hardness of the asphalt base. Ingeneral, however, the blending and related figures may be described asfalling within the following limits.

Degree of overblowing of asphaltic base 5 to 100' degrees F. v(It. 8:B.)

Physical characteristics of cutback oil "Viscosity 40" S. U. V. 100 to40,000" S. U. V

210 F. 4 V. 1. --50 minimum. Percentage of cutback oil added, 5% to Inorder to give a clear idea of an acceptable asphalt saturant, thefollowing is a typical specification as used in many industries.

Example Soft. point (R. 8; B.) ISO-160 F. Penetration:

@ 77/100/5 15-25 32/200/60 '5 115/50/5 max.

Foam break, seconds 420 max. (7 min) The roofing, linoleum and similarindustries where asphalt'saturants are used, have adopted a practicallaboratory test for the evaluation of asphalts from the standpoint offoaming characteristics. This test, while not endorsed by the AmericanSociety of Testing Materials, or any similar recognized organization,has found wide application in industrial laboratories. This test can bedescribed. as follows:

250 grams of asphalt are weighed into a 1000 cc. high type glass beakerand heated to 400 F. on an oil bath. The level of the oil bath should.be below the level of the asphalt and care should be taken that the oillevelnever rises above the level of the asphalt. An oil bath temperatureof about 435 F. should maintain the proper asphalt temperature but thiswill have to be determined for the particular apparatus as nothermometer should be in the asphalt during the test.

Using a 3" x 12" piece of 40-point feltplace 0.25 cc. of water on eachside not more than one saturant prepared from Mexican crude and meetingthe above specifications previously given.

Column 2 represents an asphalt saturant prepared by blowing a 50/50blend of Duo-Sol tar and a straight run residuum from 2. Coastal crude.This material is unsatisfactory with respect to foaming characteristics.

Column 3 represents a material produced by blending 74% of Duo-Sol tarblown to 180 softeningpoint and cut back with 26% of the same straightrun residuum from a Coastal crude as in column 2. This material isequivalent to that represented by column 1.

Column 4 represents an asphalt saturant produced by steam refining(vacuum distilling) Duo- Table II D. S. tar/coastal Bl. D. S. tar St.Ref. D. S. tar s g residuum blown +coastal +coastal m after mix residuumresiduum MP (R. and 13. .F 150 153 152 150. 5 Penetration:

A 11 a0 11 15 7 9 8 6 74 63 67 75 3 2,! W 48!! 4! 6! 25!! inch from oneend. Allow the water to soak in -one minute, then submerge the wet endof the felt in the asphalt and hold '15 sec. Remove the felt and notethe time for the first break of bubbles to give a clear surface. As thefoam breaks there will finally be ,a single layer of bubbles on thesurface, then suddenly this layer will break revealing the surface ofthe asphalt. This is the end point.

Inasmuch as the results of the foaming test are expressed interms oftime necessary for the foaming to subside. a '7 minute asphalt wouldindicate a saturant with considerably poorer foaming characteristicsthan a 3 minute asphalt. A 3 minute asphalt may be considered as anexample of anexcellent non-foaming saturant, and 4-5 minute as good; andabove 9 unsatisfactory.

In order to show results of compounding asphalt saturants as taughtherein in comparison with other methods, the following data is given, inwhich a solvent tar derived from a Duo-Sol or counter-currentpropane-cresylic acid solvent treatment of a long residuum from mixedbase crude was used, together with a straight run Coastal residuum.These starting materials had the following properties:

The following table includes the physical char- 'acteristicof fourasphalt saturants.

Column one represents a conventional asphalt Composition Foam 01% 158.5F. soft point blown Duosol tar.

9'7 residual Coastal oil...

37 196 F. soft point blown Duosol tar" 03 a 129 F. soft point steamrefined asphalt from 'Ialco crude.

}6 min. 23 sec. }7 min.

Itwill be noted that these represent saturants with foaming"characteristics which are acceptable, though not highly satisfactory.In other words, they illustrate approaches to the previously mentionedlimits of blending. In Example A, almost the minimum of cutback that canbe used is illustrated and in B, the maximum is similarly illustrated.Obviously as more cutback is used, it must itself be more nearly of thedesired saturant specification as to soft point, and if used to excess,its character predominates, and the mixture becomes merely thenon-satisfactory foaming saturant produced from ill-chosen startingmaterials by the prior art.

We claim:

1. A method for avoiding excessive foaming in the saturation ofmoisture-containing fibrous material with asphalt at a temperature atwhich evaporation of moisture contained in said material normally tendsto produce excessive foaming comprising submerging amoisture-containing'fibrous material to be saturated in a heated bath ofan asphaltic material produced by re-- ducing a petroleum fractionhaving a viscosity-,

gravity-constant of at least .890 to an asphalt having a hardness of atleast about-5 I". (R. I: B. soft point) greater than that desired forthe finished saturant, and cutting the asphalt back to desired saturantspecifications with a less viaevaporation of moisture contained in saidmacous oil having a viscosity index of at least -50.-

2. A method for avoiding excessive foaming in the saturation ofmoisture-containing fibrous material with asphalt at a temperature atwhich evaporation of moisture contained in said material normally tendsto produce excessive foaming comprising submerging a moisture-containingfibrous material to be saturated in a heated bath of an asphalticmaterial produced by reducing a petroleum fraction having aviscosity-gravityconstant of at least .890 to an asphalt having ahardness of at least about 5 F. (R. I: B. soft terial normally tends toproduce excessive foaming comprising submerging a moisture-containingfibrous material to'be saturated in' a heatebath of an asphalticmaterial produced by reducing a residual petroleum fraction havingwapoint) greater than that desired for the finished saturant, and cuttingthe asphalt back to desired saturant specifications by blending from 95to 25 parts of the asphalt with from 5 to '15 parts of a less viscousoil having a viscosity index of at least 50.

3. A method for avoiding excessive foaming in the saturation ofmoisture-containing fibrous material with asphalt at a temperature atwhich evaporation of moisture contained in said material normally tendsto produce excessive foaming comprising submerging a moisture-containingfibrous material to be saturated in a heated bath of an asphalticmaterial produced by reducing solvent tar derived from petroleum, whichsolvent tar has a vlscosity-gravity-constant of at least .890 to anasphalt having a hardness of at least about 5 F. (R. 81 B. soft point)greater viscosity-gravity-constant of at least .890 to an asphalt havinga hardness of at'least about 5.

F. (R... 8: B. soft point) greater than that desired for the finishedsaturant, and cutting the asphalt back to desired saturantspecifications with a less viscous oil having a viscosity index of atleast --50.

5. A method for avoiding excessive foaming in the saturation ofmoisture-containing fibrous material with asphalt at a temperature atwhich evaporation of moisture contained in said material normally tendsto produce excessive foaming comprising submerging a moisture-containingfibrous material to be saturated in a heated bath of anasphaltic'material produced by blowing a "Duo-Sol tar, having aviscosity-gravityconstant of at least .890 to an asphalt having ahardness of at least about 5 F. Re 8: 8. soft point) greater than thatdesired for the finished asphalt saturant, and cutting back the asphaltto desired saturant specifications by adding at least five percent of aless viscous oil thereto.

. v WALLACE E. SPELSHOUSE.

ARTHUR H. BOENAU.

